| changes in plasma progesterone and prolactin concentrations during the annual cycle and the role of prolactin in the maintenance of lactation and luteal development in the antarctic fur seal (arctocephalus gazella). | progesterone in antarctic fur seals was undetectable from 1-2 days before parturition to 4-6 days after parturition. there was a rapid increase in progesterone to 20 ng/ml between 6 and 10 days post partum and this increase coincided with peak concentrations of oestradiol-17 beta at the time normally associated with oestrus and mating in this species. newly formed corpora lutea were present in the ovaries by day 9 post partum even though the seals had been isolated in an enclosure and not mated. ... | 1991 | 2013883 |
| pathology and bacteriology of adult male antarctic fur seals, arctocephalus gazella, dying at bird island, south georgia. | a high mortality rate occurs in antarctic fur seal males on the breeding breaches of bird island, south georgia. the main causes of death were infections of fighting wounds and pneumonias. the bacteria involved appear to be opportunistic pathogens, predominantly various strains of streptococci. | 1989 | 2736383 |
| pathology of the antarctic fur seal (arctocephalus gazella) in south georgia. | | 1984 | 6722508 |
| amino acid composition of pinniped milk. | the total amino acid concentration and the amino acid pattern, i.e. the relative proportion of each amino acid (protein-bound plus free) to the total amino acids, in the milks of the northern elephant seal, antarctic fur seal, california sea lion, and australian sea lion were determined. total amino acid concentration was 10% (w/v) or greater and did not vary significantly among species. the most abundant amino acids in the milks of all species were glutamate, proline and leucine. essential amin ... | 1995 | 7584837 |
| the metabolic characteristics of the locomotory muscles of grey seals (halichoerus grypus), harbour seals (phoca vitulina) and antarctic fur seals (arctocephalus gazella). | it is not known precisely how marine mammals are able to maintain muscle function during active swimming in breath-hold dives, when ventilation stops and heart rate falls. examination of muscle biochemistry and histochemistry can provide information on the relative importance of different metabolic pathways, the contractile potential of the muscle fibres, the oxygen storage capacity of the muscle and the capillary distribution in these animals. in this study, samples of locomotory muscle were ta ... | 1994 | 7964404 |
| concentrations, metabolic clearance rates, production rates and plasma binding of cortisol in antarctic phocid seals. | we have reported previously that plasma of the weddell seal, a member of the phocid family, contains a very high concentration of cortisol. the present study was undertaken to determine whether high cortisol levels were common to seals in the antarctic environment, or to other phocidae, and to determine the mechanism of the hypercortisolaemia. high levels of cortisol (0.82-2.38 mumol/l) were found in 4 phocidae (weddell, crabeater, leopard and southern elephant seals), whereas levels in a member ... | 1993 | 8237255 |
| dental and mandibular injury in an antarctic fur seal, arctocephalus gazella, at heard island, southern ocean. | the skull of an adult male antarctic fur seal (arctocephalus gazella) collected at heard island, southern ocean, october 1992, had chronic changes attributable to a fracture of the left lower canine, luxation of the mental symphysis, osteomyelitis of the left and right mandibles, and periostitis of the left maxilla. | 1996 | 8722284 |
| the use of data loggers to determine the energetics and physiology of aquatic birds and mammals. | by deploying a data logger specifically designed for the purpose, it was possible to record heart rate, fh (beats/min), from free-ranging gentoo penguins, pygoscelis papua, and antarctic fur seals, arctocephalus gazella, at the british antarctic survey base at bird island. the heart rate data were then converted into oxygen consumption (vo2, mlo2 min-1 kg-1) and/or energy expenditure (w/kg) using equations that had been derived from calibration experiments. in these experiments the relationships ... | 1995 | 8728860 |
| genetic variation of southern hemisphere fur seals (arctocephalus spp.): investigation of population structure and species identity. | we have examined phylogenetic and geographic patterns of variation in the mitochondrial cytochrome b gene of southern hemisphere fur seals (arctocephalus spp.). our survey of 106 individuals from four putative species reveals three distinct patterns of variation reflecting ancient, recent historic, and contemporary gene flow. for the combined samples of subantarctic (arctocephalus tropicalis) and antarctic (arctocephalus gazella) fur seals, we find low levels of sequence diversity and reciprocal ... | 1997 | 9183848 |
| distribution and abundance of the tick ixodes uriae in a diverse subantarctic seabird community. | at bird island, south georgia, we surveyed the distribution and abundance of ticks on the vertebrate fauna and found only 1 species ixodes uriae. we classified all seabird species into 3 groups: (1) seabirds nesting on the surface of the ground solitarily, in dispersed groups of a few nests, or in colonies with well-spaced nests; (2) seabirds nesting on the surface of the ground in dense colonies; and (3) seabirds nesting in dense colonies in burrows or rock crevices. we detected i. uriae only o ... | 1999 | 10207358 |
| postsealing genetic variation and population structure of two species of fur seal (arctocephalus gazella and a. tropicalis). | commercial sealing in the 18th and 19th centuries had a major impact on the antarctic and subantarctic fur seal populations (arctocephalus gazella and a. tropicalis) in the southern ocean. the intensive and unrestricted nature of the industry ensured substantial reductions in population sizes and resulted in both species becoming locally extinct at some sites. however, both species are continuing to recover, through the recolonization of islands across their former range and increasing populatio ... | 2000 | 10736028 |
| lipid composition of blood platelets and erythrocytes of southern elephant seal (mirounga leonina) and antarctic fur seal (arctocephalus gazella). | erythrocyte and blood platelet phospholipid compositions were studied in three elephant seals and two fur seals, two species of marine mammals living in the subantarctic region feeding on preys rich in (n-3) polyunsaturated fatty acids. results were compared with those reported for related species and humans. in erythrocytes, the phospholipid (pl) and cholesterol (chol) contents were lower in pinnipeds than in humans. phosphatidylcholine (pc) levels were higher in elephant seals than in fur seal ... | 2000 | 10825663 |
| salmonella in sub-antarctica: low heterogeneity in salmonella serotypes in south georgian seals and birds. | the number of human visitors to antarctica is increasing rapidly, and with it a risk of introducing infectious organisms to native animals. to study the occurrence of salmonella serotypes in sub-antarctic wildlife, faecal samples were collected from gentoo penguins, macaroni penguins, gray-headed albatrosses, black-browed albatrosses and antarctic fur seals on bird island in the south georgian archipelago during the austral summer of 1996 and 1998. in 1996, s. havana, s. typhimurium and s. enter ... | 2000 | 11117947 |
| low reproductive success in territorial male antarctic fur seals (arctocephalus gazella) suggests the existence of alternative mating strategies. | microsatellites were used to conduct an analysis of paternity of antarctic fur seals (arctocephalus gazella) from bird island, south georgia. at most, only 28% of pups at our study site could be assigned a father, even though the majority (approximately 90%) of candidate males within this colony were sampled. the behavioural and genetic evidence from this study suggests that a number of alternative mating strategies may exist within this fur seal population. holding a land-based territory confer ... | 2001 | 11298959 |
| aerobic dive limit: how often does it occur in nature? | diving animals offer a unique opportunity to study the importance of physiological constraint in their everyday behaviors. an important component of the physiological capability of any diving animal is its aerobic dive limit (adl). the adl has only been measured in a few species. the goal of this study was to estimate the aerobic dive limit from measurements of body oxygen stores and at sea metabolism. this calculated adl (cadl) was then compared to measurements of diving behavior of individual ... | 2001 | 11440864 |
| fasting metabolism in antarctic fur seal (arctocephalus gazella) pups. | the metabolism of 52-73-day old antarctic fur seal pups from bird island, south georgia, was investigated during fasting periods of normal duration while their mothers were at sea foraging. body mass decreased exponentially with pups losing 3.5-3.8% of body mass per day. resting metabolic rate also decreased exponentially from 172-197 ml (o2) x min(-1) at the beginning of the fast and scaled to m(b)(0.74) at 2.3 times the level predicted for adult terrestrial mammals of similar size. while there ... | 2001 | 11440869 |
| variation in plasma leptin levels in response to fasting in antarctic fur seals (arctocephalus gazella). | plasma leptin levels were determined in 8 lactating female and 20 pup antarctic fur seals (arctocephalus gazella) during fasting periods of normal duration. plasma leptin levels ranged from 1.35 3.19 ng x ml(-1) in lactating females and 1.79-4.80 ng x ml(-1) in pups and were not positively correlated with body mass or condition. a negative trend, however, was observed between plasma leptin levels and body condition in lactating females upon their arrival at the colony following a foraging trip ( ... | 2002 | 11824401 |
| male reproductive strategy and the importance of maternal status in the antarctic fur seal arctocephalus gazella. | although mammalian mating systems are classically characterized in terms of male competition and polygyny, it is becoming increasingly apparent that alternative male strategies and female choice may play important roles. for example, females who mate with males from a dominant dynasty risk producing inbred offspring. many pinnipeds are highly polygynous, but in some species alternative male strategies such as aquatic mating appear to be important, even when behavioral observations suggest strong ... | 2003 | 14503632 |
| kin selection may influence fostering behaviour in antarctic fur seals (arctocephalus gazella). | fostering confers obvious advantages to the offspring but is seemingly costly to the caregiver. such behaviour is particularly paradoxical in seals where the energetic investment in milk is very high and has led to the suggestion that this behaviour may have evolved through either kin selection or reciprocity. we used a combination of genetic and behavioural data to investigate whether kin selection plays a role in the fostering behaviour observed in a well-studied population of antarctic fur se ... | 2003 | 14561291 |
| the comparative energetics and growth strategies of sympatric antarctic and subantarctic fur seal pups at iles crozet. | the period of maternal dependence is a time during which mammalian infants must optimise both their growth and the development of behavioural skills in order to successfully meet the demands of independent living. the rate and duration of maternal provisioning, post-weaning food availability and climatic conditions are all factors likely to influence the growth strategies of infants. while numerous studies have documented differences in growth strategies at high taxonomic levels, few have invest ... | 2003 | 14610034 |
| ecological implications of body composition and thermal capabilities in young antarctic fur seals (arctocephalus gazella). | in comparison with other homeotherms, young recently weaned marine mammals in high latitudes face exceptional energetic demands when foraging and thermoregulating. lipids are an important source of energy and a major component of insulation that allows them to meet these demands. to examine the role of lipid stores in a high-latitude pinniped, we measured the body composition and thermoregulatory capabilities of antarctic fur seal (arctocephalus gazella) pups and yearlings by using flow-through ... | 2004 | 15449238 |
| exploring the relationship between parental relatedness and male reproductive success in the antarctic fur seal arctocephalus gazella. | recent genetic studies of natural populations have shown that heterozygosity and other genetic estimates of parental relatedness correlate with a wide variety of fitness traits, from juvenile survival and parasite resistance to male reproductive success. many of these traits involve health and survival, where the underlying mechanism may involve changes in the effectiveness of the immune system. however, for traits such as reproductive success, the likely mechanisms remain less obvious. in this ... | 2004 | 15521464 |
| microsatellite genotyping errors: detection approaches, common sources and consequences for paternal exclusion. | microsatellite genotyping errors will be present in all but the smallest data sets and have the potential to undermine the conclusions of most downstream analyses. despite this, little rigorous effort has been made to quantify the size of the problem and to identify the commonest sources of error. here, we use a large data set comprising almost 2000 antarctic fur seals arctocephalus gazella genotyped at nine hypervariable microsatellite loci to explore error detection methods, common sources of ... | 2005 | 15660949 |
| does kin selection influence fostering behaviour in antarctic fur seals (arctocephalus gazella)? | a recent observation that female antarctic fur seals foster pups born to related females raises the fascinating possibility that kin selection may promote altruistic behaviour even on a crowded breeding beach, where individual interactions are frequent and complex. however, the use of genetic markers to identify small numbers of unusually highly related individuals is fraught with difficulty due to the likely presence of genotyping errors and related problems. consequently, we examined an enlarg ... | 2005 | 16191611 |
| entanglement of antarctic fur seals at bouvetøya, southern ocean. | entanglements of antarctic fur seals arctocephalus gazella were recorded during four summers from 1996 to 2002 at the subantarctic island, bouvetøya. rates of entanglement varied between 0.024% and 0.059%. these rates are low for a pinniped population and might be because of the geographic isolation of the haulout site. an apparent decrease in the levels of entanglement over the course of the study was likely due, at least in part, to the removal of entanglements by observers. at least two-third ... | 2006 | 16797599 |
| ménage à trois on macquarie island: hybridization among three species of fur seal (arctocephalus spp.) following historical population extinction. | human-induced changes to natural systems can cause major disturbances to fundamental ecological and population processes and result in local extinctions and secondary contacts between formerly isolated species. extensive fur seal harvesting during the nineteenth century on macquarie island (subantarctic) resulted in extinction of the original population. recolonization by three species has been slow and complex, characterized by the establishment of breeding groups of antarctic and subantarctic ... | 2006 | 17032266 |
| genetic tagging reveals extreme site fidelity in territorial male antarctic fur seals arctocephalus gazella. | genetic tagging, the identification of individuals using their genotypes, provides a powerful tool for studying animals that are difficult to observe or identify using conventional techniques. however, despite being widely adopted by conservation biologists, the full potential of this approach has yet to be realized. here we used genetic recapture data to quantify male site fidelity at a colony of antarctic fur seals where an aerial walkway provides unprecedented access and individual positions ... | 2006 | 17032279 |
| multiple mating strategies explain unexpected genetic mixing of new zealand fur seals with two congenerics in a recently recolonized population. | human impacts on natural systems can cause local population extinctions, which may promote redistribution of taxa and secondary contact between divergent lineages. in mammalian populations that have mating systems shaped by polygyny and sexual selection, the potential for hybridization to ensue and persist depends on individual and demographic factors. at macquarie island, a recently formed fur seal population is comprised of both sexes of breeding antarctic (arctocephalus gazella) and subantarc ... | 2007 | 18028306 |
| a new species of parafilaroides (nematoda: filaroididae) in three species of fur seals (carnivora: otariidae) from the southern hemisphere. | blocks of frozen lungs of 2 australian fur seals (arctocephalus pusillus doriferus wood jones, 1925), 2 new zealand fur seals (a. forsteri [lesson, 1828]), and 1 sub-antarctic fur seal (a. tropicalis [gray, 1872]) from 3 different locations (australia, new zealand, and south africa, respectively) were examined and found to contain lung parasites. this represents the first thorough description and identification of a new species, parafilaroides normani, from an eared seal (otariidae) in the south ... | 2009 | 18652523 |
| getting long in the tooth: a strong positive correlation between canine size and heterozygosity in antarctic fur seals arctocephalus gazella. | most studies of heterozygosity-fitness correlations (hfcs) in natural populations relate to fitness traits expressed early in life, whereas traits that are often more difficult to measure such as longevity and adult body size remain elusive. teeth provide a window on an individual's life history, allowing the reliable estimation of both age and body size. consequently, we collected paired upper canine teeth and tissue samples from 84 adult male antarctic fur seals arctocephalus gazella that died ... | 2010 | 20457622 |
| exploring the mechanisms underlying a heterozygosity-fitness correlation for canine size in the antarctic fur seal arctocephalus gazella. | although heterozygosity-fitness correlations (hfcs) are widely reported in the literature, most studies use too few markers to allow the proximate mechanisms to be convincingly resolved. two competing hypotheses have been proposed: the general effect hypothesis, in which marker heterozygosity correlates with genome-wide heterozygosity and hence the inbreeding coefficient f, and the local effect hypothesis, in which one or more of the markers by chance exhibit associative overdominance. to explor ... | 2010 | 20457623 |
| isolation and characterization of campylobacter spp. from antarctic fur seals (arctocephalus gazella) at deception island, antarctica. | the presence of campylobacter spp. was investigated in 41 antarctic fur seals (arctocephalus gazella) and 9 weddell seals (leptonychotes weddellii) at deception island, antarctica. infections were encountered in six antarctic fur seals. the isolates, the first reported from marine mammals in the antarctic region, were identified as campylobacter insulaenigrae and campylobacter lari. | 2010 | 20639356 |
| gene discovery in the antarctic fur seal (arctocephalus gazella) skin transcriptome. | next-generation sequencing provides a powerful new approach for developing functional genomic tools for nonmodel species, helping to narrow the gap between studies of model organisms and those of natural populations. consequently, massively parallel 454 sequencing was used to characterize a normalized cdna library derived from skin biopsy samples of twelve antarctic fur seal (arctocephalus gazella) individuals. over 412 mb of sequence data were generated, comprising 1.4 million reads of average ... | 2011 | 21466659 |
| treatment and prevention of infection following bites of the antarctic fur seal (arctocephalus gazella). | in recent decades, an increasing number of people have traveled to sub-antarctic and antarctic regions each year for research, tourism, and resource exploitation. hunting of antarctic fur seals (arctocephalus gazella) almost pushed the species to extinction in the early 1900s, but populations have since shown rapid and substantial recovery. the species' range has re-expanded to include several islands south of the antarctic convergence, most notably south georgia, and now overlaps with many popu ... | 2015 | 27147885 |
| identification of respiratory and gastrointestinal parasites of three species of pinnipeds (arctocephalus australis, arctocephalus gazella, and otaria flavescens) in southern brazil. | in order to improve understanding of parasitism in south american pinnipeds, respiratory and gastrointestinal samples were collected from 12 arctocephalus australis (south american fur seal), one arctocephalus gazella (antarctic fur seal), and one otaria flavescens (south american sea lion). ova and larvae were microscopically identified from fecal samples and respiratory secretions collected from live a. australis undergoing rehabilitation at centro de recuperação de animais marinhos (cram-furg ... | 2016 | 27010274 |
| serum chemistry and antibodies against pathogens in antarctic fur seals, weddell seals, crabeater seals, and ross seals. | information on health parameters, such as antibody prevalences and serum chemistry that can reveal exposure to pathogens, disease, and abnormal physiologic conditions, is scarce for antarctic seal species. serum samples from antarctic fur seals (arctocephalus gazella, n=88) from bouvetøya (2000-2001 and 2001-2002), and from weddell seals (leptonychotes weddellii, n=20), ross seals (ommatophoca rossii, n=20), and crabeater seals (lobodon carcinophagus, n=9) from the pack-ice off queen maud land, ... | 2012 | 22740529 |
| detection of toxoplasma gondii antibodies in antarctic pinnipeds. | the presence of toxoplasma gondii antibodies was investigated in antarctic marine mammals. two hundred and eleven sera from different species of pinnipeds collected in years 2007, 2010 and 2011 from different locations in the south shetland islands and antarctic peninsula were analysed using a commercially available agglutination test kit. the presence of antibodies (titres ≥ 1:25) against t. gondii was detected in a total of 28 animals (13.3%). amongst animal species, percentages of detection w ... | 2012 | 22726387 |
| myth or relict: does ancient dna detect the enigmatic upland seal? | the biological status of the so-called 'upland seal' has remained contentious ever since historical records described a distinct seal from the uplands of new zealand's (nz) remote sub-antarctic islands. subsequent genetic surveys of the nz fur seal (arctocephalus forsteri) detected two highly-divergent mtdna clades, hypothesized to represent a post-sealing hybrid swarm between 'mainland' (australia-nz; a. forsteri) and sub-antarctic (putative 'upland'; a. snaresensis) lineages. we present ancien ... | 2016 | 26768113 |
| breeding success of a marine central place forager in the context of climate change: a modeling approach. | in response to climate warming, a southward shift in productive frontal systems serving as the main foraging sites for many top predator species is likely to occur in subantarctic areas. central place foragers, such as seabirds and pinnipeds, are thus likely to cope with an increase in the distance between foraging locations and their land-based breeding colonies. understanding how central place foragers should modify their foraging behavior in response to changes in prey accessibility appears c ... | 2017 | 28355282 |
| early-life sexual segregation: ontogeny of isotopic niche differentiation in the antarctic fur seal. | investigating the ontogeny of niche differentiation enables to determine at which life-stages sexual segregation arises, providing insights into the main factors driving resource partitioning. we investigated the ontogeny of foraging ecology in antarctic fur seals (arctocephalus gazella), a highly dimorphic species with contrasting breeding strategies between sexes. sequential δ(13)c and δ(15)n values of whiskers provided a longitudinal proxy of the foraging niche throughout the whole life of se ... | 2016 | 27620663 |
| transcriptomic snp discovery for custom genotyping arrays: impacts of sequence data, snp calling method and genotyping technology on the probability of validation success. | single nucleotide polymorphism (snp) discovery is an important goal of many studies. however, the number of 'putative' snps discovered from a sequence resource may not provide a reliable indication of the number that will successfully validate with a given genotyping technology. for this it may be necessary to account for factors such as the method used for snp discovery and the type of sequence data from which it originates, suitability of the snp flanking sequences for probe design, and genomi ... | 2016 | 27562535 |
| born blonde: a recessive loss-of-function mutation in the melanocortin 1 receptor is associated with cream coat coloration in antarctic fur seals. | although the genetic basis of color variation has been extensively studied in humans and domestic animals, the genetic polymorphisms responsible for different color morphs remain to be elucidated in many wild vertebrate species. for example, hypopigmentation has been observed in numerous marine mammal species but the underlying mutations have not been identified. a particularly compelling candidate gene for explaining color polymorphism is the melanocortin 1 receptor (mc1r), which plays a key ro ... | 2016 | 27547348 |
| mating success and body condition not related to foraging specializations in male fur seals. | individual specialization is widespread among wild populations. while its fitness consequences are central in predicting the ecological and evolutionary trajectories of populations, they remain poorly understood. long-term individual foraging specializations occur in male antarctic (arctocephalus gazella) and australian (a. pusillus doriferus) fur seals. strong selective pressure is expected in these highly dimorphic and polygynous species, raising the question of the fitness payoffs associated ... | 2016 | 27493771 |
| offspring hormones reflect the maternal prenatal social environment: potential for foetal programming? | females of many species adaptively program their offspring to predictable environmental conditions, a process that is often mediated by hormones. laboratory studies have shown, for instance, that social density affects levels of maternal cortisol and testosterone, leading to fitness-relevant changes in offspring physiology and behaviour. however, the effects of social density remain poorly understood in natural populations due to the difficulty of disentangling confounding influences such as cli ... | 2016 | 26761814 |
| a draft fur seal genome provides insights into factors affecting snp validation and how to mitigate them. | custom genotyping arrays provide a flexible and accurate means of genotyping single nucleotide polymorphisms (snps) in a large number of individuals of essentially any organism. however, validation rates, defined as the proportion of putative snps that are verified to be polymorphic in a population, are often very low. a number of potential causes of assay failure have been identified, but none have been explored systematically. in particular, as snps are often developed from transcriptomes, par ... | 2016 | 26683564 |
| mother vocal recognition in antarctic fur seal arctocephalus gazella pups: a two-step process. | in otariids, mother's recognition by pups is essential to their survival since females nurse exclusively their own young and can be very aggressive towards non-kin. antarctic fur seal, arctocephalus gazella, come ashore to breed and form dense colonies. during the 4-month lactation period, females alternate foraging trips at sea with suckling period ashore. on each return to the colony, females and pups first use vocalizations to find each other among several hundred conspecifics and olfaction i ... | 2015 | 26331475 |
| assessing the effectiveness of specially protected areas for conservation of antarctica's botanical diversity. | vegetation is sparsely distributed over antarctica's ice-free ground, and distinct plant communities are present in each of the continent's 15 recently identified antarctic conservation biogeographic regions (acbrs). with rapidly increasing human activity in antarctica, terrestrial plant communities are at risk of damage or destruction by trampling, overland transport, and infrastructure construction and from the impacts of anthropogenically introduced species, as well as uncontrollable pressure ... | 2016 | 26205208 |
| the impact of predation by marine mammals on patagonian toothfish longline fisheries. | predatory interaction of marine mammals with longline fisheries is observed globally, leading to partial or complete loss of the catch and in some parts of the world to considerable financial loss. depredation can also create additional unrecorded fishing mortality of a stock and has the potential to introduce bias to stock assessments. here we aim to characterise depredation in the patagonian toothfish (dissostichus eleginoides) fishery around south georgia focusing on the spatio-temporal compo ... | 2015 | 25738698 |
| determinants of individual foraging specialization in large marine vertebrates, the antarctic and subantarctic fur seals. | the degree of individual specialization in resource use differs widely among wild populations where individuals range from fully generalized to highly specialized. this interindividual variation has profound implications in many ecological and evolutionary processes. a recent review proposed four main ecological causes of individual specialization: interspecific and intraspecific competition, ecological opportunity and predation. using the isotopic signature of subsampled whiskers, we investigat ... | 2015 | 25649011 |
| inter-annual variation of persistent organic pollutants (pops) in an antarctic top predator arctocephalus gazella. | persistent organic pollutants (pops), contaminants that may bioaccumulate in upper trophic level organisms, were detected in the milk of a top predator, the antarctic fur seal (arctocephalus gazella). multiparous females had significantly lower concentrations of certain pops (trans-nonachlor, p,p'-dde, and several pcbs) in their milk than primiparous females, likely due to the annual lactational transfer of the pop burden from mother to pup. furthermore, there were significant interannual differ ... | 2013 | 24138491 |
| brucella antibody seroprevalence in antarctic seals (arctocephalus gazella, leptonychotes weddellii and mirounga leonina). | brucellosis is a worldwide infectious zoonotic disease caused by gram-negative bacteria of the genus brucella, and brucella infections in marine mammals were first reported in 1994. a serosurvey investigating the presence of anti-brucella antibodies in 3 antarctic pinniped species was undertaken with a protein a/g indirect enzyme-linked immunosorbent assay (ielisa) and the rose bengal test (rbt). serum samples from 33 weddell seals leptonychotes weddelli were analysed, and antibodies were detect ... | 2013 | 23999701 |
| entanglement of antarctic fur seals at bird island, south georgia. | between november 1989 and march 2013, 1033 antarctic fur seals arctocephalus gazella were observed entangled in marine debris at bird island, south georgia. the majority of entanglements involved plastic packaging bands (43%), synthetic line (25%) or fishing net (17%). juvenile male seals were the most commonly entangled (44%). a piecewise regression analysis showed that a single breakpoint at 1994 gave the best description of inter-annual variability in the data, with higher levels of entanglem ... | 2013 | 23915979 |
| cross-amplification and validation of snps conserved over 44 million years between seals and dogs. | high-density snp arrays developed for humans and their companion species provide a rapid and convenient tool for generating snp data in closely-related non-model organisms, but have not yet been widely applied to phylogenetically divergent taxa. consequently, we used the caninehd beadchip to genotype 24 antarctic fur seal (arctocephalus gazella) individuals. despite seals and dogs having diverged around 44 million years ago, 33,324 out of 173,662 loci (19.2%) could be genotyped, of which 173 wer ... | 2013 | 23874599 |
| top-down and bottom-up influences on demographic rates of antarctic fur seals arctocephalus gazella. | two major drivers in population dynamics are bottom-up processes, such as environmental factors that affect foraging success, and the top-down impacts of predation. many populations of marine mammal and seabird species appear to be declining in response to reductions in prey associated with the bottom-up effects of climate change. however, predation, which usually occurs at sea and is difficult to observe, may also play a key role. we analysed drivers of population dynamics of antarctic fur seal ... | 2013 | 23444975 |
| transcriptome of the dead: characterisation of immune genes and marker development from necropsy samples in a free-ranging marine mammal. | | 2013 | 23347513 |
| persistent organic pollutants and stable isotopes in pinnipeds from king george island, antarctica. | in the present work, fat, skin, liver and muscle samples from leptonychotes weddellii (weddell seal, n=2 individuals), lobodon carcinophagus (crabeater seal, n=2), arctocephalus gazella (antarctic fur seal, n=3) and mirounga leonina (southern elephant seal, n=1) were collected from king george island, antarctica, and analysed for pops (pcbs, organochlorine pesticides and pbdes) and stable isotopes (δ¹³c and δ¹⁵n in all tissues but fat). pbdes could be found in only one sample (l. weddellii fat). ... | 2012 | 23154138 |
| rates of assay success and genotyping error when single nucleotide polymorphism genotyping in non-model organisms: a case study in the antarctic fur seal. | although single nucleotide polymorphisms (snps) are increasingly being recognized as powerful molecular markers, their application to non-model organisms can bring significant challenges. among these are imperfect conversion rates of assays designed from in silico resources and the enhanced potential for genotyping error relative to pre-validated, highly optimized human snps. to explore these issues, we used illumina's goldengate assay to genotype 480 antarctic fur seal (arctocephalus gazella) i ... | 2012 | 22727236 |
| a bayesian hierarchical model of antarctic fur seal foraging and pup growth related to sea ice and prey abundance. | we created a bayesian hierarchical model (bhm) to investigate ecosystem relationships between the physical ecosystem (sea ice extent), a prey measure (krill density), predator behaviors (diving and foraging effort of female antarctic fur seals, arctocephalus gazella, with pups) and predator characteristics (mass of maternal fur seals and pups). we collected data on antarctic fur seals from 1987/1988 to 1994/1995 at seal island, antarctica. the bhm allowed us to link together predators and prey i ... | 2012 | 22611863 |
| dynamic influence of maternal and pup traits on maternal care during lactation in an income breeder, the antarctic fur seal. | life-history theory predicts that selection will favor optimal levels of parental effort that balance benefits of current reproduction with costs to survival and future reproduction. the optimal level of effort depends on parental traits, offspring traits, and provisioning strategy. additionally, how these factors influence effort may differ depending on the stage of reproduction. the relative importance of maternal and offspring traits on energy allocation to offspring was investigated in known ... | 2012 | 22494980 |
| long-term species, sexual and individual variations in foraging strategies of fur seals revealed by stable isotopes in whiskers. | individual variations in the use of the species niche are an important component of diversity in trophic interactions. a challenge in testing consistency of individual foraging strategy is the repeated collection of information on the same individuals. | 2012 | 22431988 |
| relative changes in krill abundance inferred from antarctic fur seal. | antarctic krill euphausia superba is a predominant species in the southern ocean, it is very sensitive to climate change, and it supports large stocks of fishes, seabirds, seals and whales in antarctic marine ecosystems. modern krill stocks have been estimated directly by net hauls and acoustic surveys; the historical krill density especially the long-term one in the southern ocean, however, is unknown. here we inferred the relative krill population changes along the west antarctic peninsula (wa ... | 2011 | 22087294 |
| bayesian inference of a historical bottleneck in a heavily exploited marine mammal. | emerging bayesian analytical approaches offer increasingly sophisticated means of reconstructing historical population dynamics from genetic data, but have been little applied to scenarios involving demographic bottlenecks. consequently, we analysed a large mitochondrial and microsatellite dataset from the antarctic fur seal arctocephalus gazella, a species subjected to one of the most extreme examples of uncontrolled exploitation in history when it was reduced to the brink of extinction by the ... | 2011 | 21895820 |
| a novel approach for mining polymorphic microsatellite markers in silico. | an important emerging application of high-throughput 454 sequencing is the isolation of molecular markers such as microsatellites from genomic dna. however, few studies have developed microsatellites from cdna despite the added potential for targeting candidate genes. moreover, to develop microsatellites usually requires the evaluation of numerous primer pairs for polymorphism in the focal species. this can be time-consuming and wasteful, particularly for taxa with low genetic diversity where th ... | 2011 | 21853104 |
| recursive filtering for zero offset correction of diving depth time series with gnu r package divemove. | zero offset correction of diving depth measured by time-depth recorders is required to remove artifacts arising from temporal changes in accuracy of pressure transducers. currently used methods for this procedure are in the proprietary software domain, where researchers cannot study it in sufficient detail, so they have little or no control over how their data were changed. gnu r package divemove implements a procedure in the free software domain that consists of recursively smoothing and filter ... | 2011 | 21297976 |
| permanent genetic resources: ten novel polymorphic dinucleotide microsatellite loci cloned from the antarctic fur seal arctocephalus gazella. | ten new dinucleotide microsatellite loci were isolated from the antarctic fur seal arctocephalus gazella. these markers should prove useful for studying the reproductive ecology of antarctic fur seals and other related pinniped species. | 2008 | 21585821 |
| no relationship between microsatellite variation and neonatal fitness in antarctic fur seals, arctocephalus gazella. | published studies of wild vertebrate populations have almost universally reported positive associations between genetic variation measured at microsatellite loci and fitness, creating the impression of ubiquity both in terms of the species and the traits involved. however, there is concern that this picture may be misleading because negative results frequently go unpublished. here, we analyse the relationship between genotypic variation at nine highly variable microsatellite loci and neonatal fi ... | 2006 | 16689914 |
| characterisation of proteins in the milk of fur seals. | milk protein composition was investigated throughout the lactation periods of the australian fur seal (arctocephalus pusillus doriferus) and antarctic fur seal (arctocephalus gazella). the mean protein content of the milk was found to be 10.9% and 10.6% respectively. the concentration of total protein did not change during lactation, although a decline in casein content of the milk in late lactation was apparent. milk protein concentration during a foraging/suckling cycle of the antarctic fur se ... | 2005 | 15820141 |
| how mothers find their pups in a colony of antarctic fur seals. | in antarctic fur seals, arctocephalus gazella, mothers must identify their own young among hundreds or even thousands of pups, if they are to invest in their own offspring and avoid misdirecting their parental care. when returning to their breeding colony from a foraging trip of several days at sea, mothers have to find and identify their young before suckling can occur. there appears to be little confusion about which pup belongs to a mother, and adoption is absent or rare. using behavioral obs ... | 2003 | 12543485 |
| skin temperatures during free-ranging swimming and diving in antarctic fur seals. | this study tests the hypothesis that an endothermic homeotherm should minimise heat flux in cold polar waters by minimising skin temperature. temperature variability was measured at the surface of the skin of three antarctic fur seals (arctocephalus gazella) at intervals of 2 s over a total of 9.7 days while they were swimming and diving freely in polar waters at temperatures of 1.5-4 degrees c. the temperature difference ( capdelta t) between skin on the dorsal thorax and the water varied from ... | 2000 | 10821747 |
| relative abundance and behavior of marine mammals exposed to transmissions from the heard island feasibility test. | the heard island feasibility test source transmitted a hum at 209-220 db re: 1 micropa at 175-m depth, centered on 57 hz with a maximum bandwidth of 30 hz for 1 h of every 3. experienced marine mammal observers conducted line-transect surveys and monitored marine mammal behavior visually and acoustically in a 70 x 70 km square centered on the transmission site. thirty-nine groups of cetaceans and 19 of pinnipeds were sighted from both vessels before the start of transmissions. thirty-nine groups ... | 1994 | 7963037 |
| positional analyses of triacylglycerol fatty acids in the milk fat of the antarctic fur seal (arctocephalus gazella). | the positional distribution of fatty acids has been determined for the milk triacylglycerols of the antarctic fur seal, arctocephalus gazella. of particular interest was the positional distribution of the polyunsaturated n-3 fatty acids in milk triacylglycerols (tg). in adipocytes of pinnipeds, tg are synthesized with the n-3 fatty acids primarily in the sn-1,3 positions. to determine the positional distribution, extracts of enzymatically digested lipids were separated by thin-layer chromatograp ... | 1992 | 1406076 |
| interspecies sexual behaviour between a male japanese macaque and female sika deer. | interspecies sexual behaviour or 'reproductive interference' has been reported across a wide range of animal taxa. however, most of these occurrences were observed in phylogenetically close species and were mainly discussed in terms of their effect on fitness, hybridization and species survival. the few cases of heterospecific mating in distant species occurred between animals that were bred and maintained in captivity. only one scientific study has reported this phenomenon, describing sexual ha ... | 2017 | 28074343 |
| mercury in the ecosystem of admiralty bay, king george island, antarctica: occurrence and trophic distribution. | mercury (hg) can reach the environment through natural and human-related sources, threatening ecosystems all over the planet due to its well known deleterious effects. therefore, antarctic trophic webs, despite being relatively isolated, are not exempt of its influence. to evaluate hg concentrations in an antarctic ecosystem, different tissues from 2 species of invertebrates, 2 of fish, 8 of birds, 4 of pinnipeds and at least 5 of vegetation were investigated (n=176). for animals, values ranged ... | 2017 | 27717573 |
| stable isotopes document seasonal changes in trophic niches and winter foraging individual specialization in diving predators from the southern ocean. | 1. climatic variation outside the breeding season affects fluctuations in population numbers of seabirds and marine mammals. a challenge in identifying the underlying biological mechanisms is the lack of information on their foraging strategies during winter, when individuals migrate far from their breeding grounds. 2. we investigated the temporal variability in resource partitioning within the guild of five sympatric subantarctic penguins and fur seals from crozet islands. the stable isotopic r ... | 2007 | 17584388 |
| contamination profiles of selected pcb congeners, chlorinated pesticides, pcdd/fs in antarctic fur seal pups and penguin eggs. | the aim of this study was to investigate levels of some major environmental contaminants, such as polychlorinated biphenyls (pcbs), polychlorinated dibenzo-p-dioxins and dibenzofurans (pcdd/fs) and organochlorine pesticides in antarctic samples. concentrations of some persistent organic pollutants (pops) were investigated in antarctic fur seal pups and eggs of three species of penguins. dichloro-diphenyl-trichloroethane (ddt) was the main pollutant, followed by pcbs; other organochlorine compoun ... | 2009 | 19375148 |
| perfluorinated contaminants in fur seal pups and penguin eggs from south shetland, antarctica. | perfluorinated compounds (pfcs) have emerged as a new class of global environmental pollutants. in this study, the presence of perfluorochemicals (pfcs) in penguin eggs and antarctic fur seals was reported for the first time. tissue samples from antarctic fur seal pups and penguin eggs were collected during the 2003/04 breeding season. ten pfc contaminants were determined in seal and penguin samples. the pfc concentrations in seal liver were in the decreasing order, pfos>pfna>pfhpa>pfunda while ... | 2009 | 19321191 |
| analysis of zp1 gene reveals differences in zona pellucida composition in carnivores. | the zona pellucida (zp) is an extracellular envelope that surrounds mammalian oocytes. this coat participates in the interaction between gametes, induction of the acrosome reaction, block of polyspermy and protection of the oviductal embryo. previous studies suggested that carnivore zp was formed by three glycoproteins (zp2, zp3 and zp4), with zp1 being a pseudogene. however, a recent study in the cat found that all four proteins were expressed. in the present study, in silico and molecular anal ... | 2017 | 28679462 |
| genome sequence of a novel picorna-like rna virus from feces of the antarctic fur seal (arctocephalus gazella). | a novel rna virus was detected in a fecal sample collected from the antarctic fur seal (arctocephalus gazella) in king george island, antarctica. the almost-complete genome sequence reveals two open reading frames and a dicistrovirus-like gene order. | 2017 | 28883153 |
| correction: return customers: foraging site fidelity and the effect of environmental variability in wide-ranging antarctic fur seals. | [this corrects the article doi: 10.1371/journal.pone.0120888.]. | 2017 | 28586381 |
| activity-specific metabolic rates for diving, transiting, and resting at sea can be estimated from time-activity budgets in free-ranging marine mammals. | time and energy are the two most important currencies in animal bioenergetics. how much time animals spend engaged in different activities with specific energetic costs ultimately defines their likelihood of surviving and successfully reproducing. however, it is extremely difficult to determine the energetic costs of independent activities for free-ranging animals. in this study, we developed a new method to calculate activity-specific metabolic rates, and applied it to female fur seals. we atta ... | 2017 | 28479996 |
| reproductive success is energetically linked to foraging efficiency in antarctic fur seals. | the efficiency with which individuals extract energy from their environment defines their survival and reproductive success, and thus their selective contribution to the population. individuals that forage more efficiently (i.e., when energy gained exceeds energy expended) are likely to be more successful at raising viable offspring than individuals that forage less efficiently. our goal was to test this prediction in large long-lived mammals under free-ranging conditions. to do so, we equipped ... | 2017 | 28453563 |
| identifying risk: concurrent overlap of the antarctic krill fishery with krill-dependent predators in the scotia sea. | mitigating direct and indirect interactions between marine predators and fisheries is a motivating factor for ecosystem-based fisheries management (ebfm), especially where predators and fisheries compete for a shared resource. one difficulty in advancing ebfm is parameterizing clear functional responses of predators to indices of prey availability. alternative characterizations of fishery-predator interactions may therefore benefit the implementation of ebfm. telemetry data identify foraging are ... | 2017 | 28085943 |
| putting the behavior into animal movement modeling: improved activity budgets from use of ancillary tag information. | animal movement research relies on biotelemetry, and telemetry-based locations are increasingly augmented with ancillary information. this presents an underutilized opportunity to enhance movement process models. given tags designed to record specific behaviors, efforts are increasing to update movement models beyond reliance solely upon horizontal movement information to improve inference of space use and activity budgets. we present two state-space models adapted to incorporate ancillary data ... | 2016 | 27878092 |
| flipper strokes can predict energy expenditure and locomotion costs in free-ranging northern and antarctic fur seals. | flipper strokes have been proposed as proxies to estimate the energy expended by marine vertebrates while foraging at sea, but this has never been validated on free-ranging otariids (fur seals and sea lions). our goal was to investigate how well flipper strokes correlate with energy expenditure in 33 foraging northern and antarctic fur seals equipped with accelerometers, gps, and time-depth recorders. we concomitantly measured field metabolic rates with the doubly-labelled water method and deriv ... | 2016 | 27658718 |
| chemical fingerprints encode mother-offspring similarity, colony membership, relatedness, and genetic quality in fur seals. | chemical communication underpins virtually all aspects of vertebrate social life, yet remains poorly understood because of its highly complex mechanistic basis. we therefore used chemical fingerprinting of skin swabs and genetic analysis to explore the chemical cues that may underlie mother-offspring recognition in colonially breeding antarctic fur seals. by sampling mother-offspring pairs from two different colonies, using a variety of statistical approaches and genotyping a large panel of micr ... | 2015 | 26261311 |
| the influence of preceding dive cycles on the foraging decisions of antarctic fur seals. | the foraging strategy of many animals is thought to be determined by their past experiences. however, few empirical studies have investigated whether this is true in diving animals. we recorded three-dimensional movements and mouth-opening events from three antarctic fur seals during their foraging trips to examine how they adapt their behaviour based on past experience--continuing to search for prey in the same area or moving to search in a different place. each dive cycle was divided into a tr ... | 2015 | 26156132 |
| return customers: foraging site fidelity and the effect of environmental variability in wide-ranging antarctic fur seals. | strategies employed by wide-ranging foraging animals involve consideration of habitat quality and predictability and should maximise net energy gain. fidelity to foraging sites is common in areas of high resource availability or where predictable changes in resource availability occur. however, if resource availability is heterogeneous or unpredictable, as it often is in marine environments, then habitat familiarity may also present ecological benefits to individuals. we examined the winter fora ... | 2015 | 25807082 |
| climate change selects for heterozygosity in a declining fur seal population. | global environmental change is expected to alter selection pressures in many biological systems, but the long-term molecular and life history data required to quantify changes in selection are rare. an unusual opportunity is afforded by three decades of individual-based data collected from a declining population of antarctic fur seals in the south atlantic. here, climate change has reduced prey availability and caused a significant decline in seal birth weight. however, the mean age and size of ... | 2014 | 25056064 |
| can we predict foraging success in a marine predator from dive patterns only? validation with prey capture attempt data. | predicting how climatic variations will affect marine predator populations relies on our ability to assess foraging success, but evaluating foraging success in a marine predator at sea is particularly difficult. dive metrics are commonly available for marine mammals, diving birds and some species of fish. bottom duration or dive duration are usually used as proxies for foraging success. however, few studies have tried to validate these assumptions and identify the set of behavioral variables tha ... | 2014 | 24603534 |
| unexpected genetic differentiation between recently recolonized populations of a long-lived and highly vagile marine mammal. | many species have been heavily exploited by man leading to local extirpations, yet few studies have attempted to unravel subsequent recolonization histories. this has led to a significant gap in our knowledge of the long-term effects of exploitation on the amount and structure of contemporary genetic variation, with important implications for conservation. the antarctic fur seal provides an interesting case in point, having been virtually exterminated in the nineteenth century but subsequently s ... | 2013 | 24198934 |
| potential climate change effects on the habitat of antarctic krill in the weddell quadrant of the southern ocean. | antarctic krill is a cold water species, an increasingly important fishery resource and a major prey item for many fish, birds and mammals in the southern ocean. the fishery and the summer foraging sites of many of these predators are concentrated between 0° and 90°w. parts of this quadrant have experienced recent localised sea surface warming of up to 0.2°c per decade, and projections suggest that further widespread warming of 0.27° to 1.08°c will occur by the late 21(st) century. we assessed t ... | 2013 | 23991072 |
| biological and environmental drivers of energy allocation in a dependent mammal, the antarctic fur seal pup. | little is known about how variation in the pattern and magnitude of parental effort influences allocation decisions in offspring. we determined the energy budget of antarctic fur seal pups and examined the relative importance of timing of provisioning, pup traits (mass, condition, sex), and weather (wind chill and solar radiation) on allocation of energy obtained in milk by measuring milk energy intake, field metabolic rate (fmr), and growth rate in 48 antarctic fur seal pups over three developm ... | 2012 | 22418706 |
| whisker isotopic signature depicts migration patterns and multi-year intra- and inter-individual foraging strategies in fur seals. | the movement and dietary history of individuals can be studied using stable isotope records in archival keratinous tissues. here, we present a chronology of temporally fine-scale data on the trophic niche of otariid seals by measuring the isotopic signature of serially sampled whiskers. whiskers of male antarctic fur seals breeding at the crozet islands showed synchronous and regular oscillations in both their delta(13)c and delta(15)n values that are likely to represent their annual migrations ... | 2009 | 19793740 |
| ascent exhalations of antarctic fur seals: a behavioural adaptation for breath-hold diving? | novel observations collected from video, acoustic and conductivity sensors showed that antarctic fur seals consistently exhale during the last 50-85% of ascent from all dives (10-160 m, n > 8000 dives from 50 seals). the depth of initial bubble emission was best predicted by maximum dive depth, suggesting an underlying physical mechanism. bubble sound intensity recorded from one seal followed predictions of a simple model based on venting expanding lung air with decreasing pressure. comparison o ... | 2005 | 15734689 |
| drinking behaviour and water turnover rates of antarctic fur seal pups: implications for the estimation of milk intake by isotopic dilution. | the estimation of milk consumption in free-ranging seals using tritium dilution techniques makes the key assumption that the animals drink no pre-formed water during the experimental period. however, frequent observations of unweaned antarctic fur seal pups drinking water at iles kerguelen necessitated the testing of this assumption. we estimated water flux rates of 30 pups (10.7+/-0.3 kg) in four experimental groups by isotopic dilution over 4 days. the groups were: (1) pups held in an open air ... | 2002 | 12020648 |
| heart rate and behavior of fur seals: implications for measurement of field energetics. | archival data loggers were used to collect information about depth, swimming speed, and heart rate in 23 free-ranging antarctic fur seals. deployments averaged 9.6 +/- 5.6 days (sd) and totaled 191 days of recording. heart rate averaged 108.7 +/- 17.7 beats/min (sd) but varied from 83 to 145 beats/min among animals. morphometrics explained most variations in heart rate among animals. these interacted with diving activity and swimming speed to produce a complex relationship between heart rate and ... | 1999 | 10070067 |
| an 85k snp array uncovers inbreeding and cryptic relatedness in an antarctic fur seal breeding colony. | high density single nucleotide polymorphism (snp) arrays allow large numbers of individuals to be rapidly and cost-effectively genotyped at large numbers of genetic markers. however, despite being widely used in studies of humans and domesticated plants and animals, snp arrays are lacking for most wild organisms. we developed a custom 85k affymetrix axiom array for an intensively studied pinniped, the antarctic fur seal (arctocephalus gazella). snps were discovered from a combination of genomic ... | 2020 | 32540866 |
| rad sequencing and a hybrid antarctic fur seal genome assembly reveal rapidly decaying linkage disequilibrium, global population structure and evidence for inbreeding. | recent advances in high throughput sequencing have transformed the study of wild organisms by facilitating the generation of high quality genome assemblies and dense genetic marker datasets. these resources have the potential to significantly advance our understanding of diverse phenomena at the level of species, populations and individuals, ranging from patterns of synteny through rates of linkage disequilibrium (ld) decay and population structure to individual inbreeding. consequently, we used ... | 2018 | 29954843 |
| novel anelloviruses identified in buccal swabs of antarctic fur seals. | viral diversity associated with antarctic wildlife remains poorly studied. nonetheless, over the past 5 years, there has been a concerted effort using viral metagenomics approaches to identify and characterize viruses associated with antarctic pinniped and avian species. here we used a viral metagenomics approach to identify circular dna viruses in buccal swab samples from antarctic fur seals (arctocephalus gazella) breeding on livingston island, antarctica during the 2016/2017 field season. we ... | 2018 | 29971737 |
| leopard seal diets in a rapidly warming polar region vary by year, season, sex, and body size. | resolving the preferred prey items and dietary proportions of leopard seals is central to understanding food-web dynamics in the rapidly-warming antarctic peninsula region. previous studies have identified a wide range of prey items; however, due to anecdotal or otherwise limited information, leopard seal diets remain unresolved by seal sex, individual, body size, region, and season. over the 2013, 2014, and 2017 field seasons we collected scat, tissue samples (red blood cells and plasma; n = 23 ... | 2020 | 32493329 |